Justification:
Listed as Critically Endangered because of a drastic population decline, estimated to be more than 80% over the last ten years, inferred from the apparent disappearance of most of the population (probably due to chytridiomycosis); and because its Area of Occupancy is less than 10 km2, all individuals are in a single location, and there is continuing decline in the number of mature individuals.

This species has a very restricted distribution of only a few square kilometres at the type locality, in the Páramo de Mucubají, in the Sierra de Santo Domingo, Venezuelan Andes. It has an altitudinal range of 2,300-3,500m asl.

It is a very rare species. This is the only Venezuelan Andean amphibian for which an ongoing population monitoring programme exists. The population seems to have experienced a drastic decline in the last 15 years or so, to the point that no individuals of this species were recorded since 1993 (adults) or 1994 (larvae), until recent surveys confirmed that a few individuals (a total of 23 encountered) continue to survive in the wild (Barrio-Amorós 2004).

This species is an inhabitant of páramo and cloud forest, the highest environments in the Venezuelan Andes, resembling alpine tundra, but with daily temperature extremes. It is usually found within grasses and frailejones (Espeletia spp.), and along streams. It probably lives in the shrubs of the sub-páramo environment. It is photophilic and lays egg chains in streams, where the tadpoles also develop.

Batrachochytrium dendrobatidis infection was confirmed for this species in two different studies (Lampo et al. 2006a, 2006b). Introduced trout, introduced conifers, fires caused by humans, over collection, and agriculture and infrastructure development for human settlement are all major threats. Severe dry periods have been associated to the declines experienced in populations of Atelopus mucubajiensis. (Lampo et al. 2006; Santiago-Paredes and La Marca 2006). The extreme dry events are thought to have favoured the infection and propagation of chytridiomycosis, which, in synergy with other factors, could be held responsible for the observed population declines.

Most of the range of this species is within the Parque Nacional Sierra Nevada. A new monitoring project for this species was recently begun (www.andigena.org). In view of the threat of chytridiomycosis, an ex-situ population might need to be established.